For instance, during the refolding process, β-lactoglobulin refolded into a specific state rich in α-helix before β-sheet formation in the denatured state (Shibayama, 2008). The incorrect refolding of TRH α-helix from the denatured state might disturb the entire protein structure and function of TRH. Alternatively, maintenance of TRH α-helix structure contents after heat denaturation may be related to the Ku-0059436 price structural stability of the amyloidogenic
proteins. Further investigations at atomic level are needed to clarify whether the correct refolding of α-helix contents from the denatured state is essential for the Arrhenius effect. Our findings indicated that the TDH and TRH showed similar hemolytic activity in vitro. Previous reports showed that the expression level of the trh gene (Kanagawa phenomenon-negative
LBH589 supplier strains) is much lower than that of the tdh gene (Kishishita et al., 1992; Okuda & Nishibuchi, 1998). These data may also account for the epidemiological finding that larger numbers of patients with TDH-positive strains are reported among the V. parahaemolyticus infections in contrast to those with TRH-positive strains. In this study, we used human red blood cells for bioassay because the Kanagawa phenomenon is the most classical and distinguishable biological assay for TDH-positive and TRH-positive clinical strains. However, TDH is reported to show cytotoxicity on various mammalian cell lines, including intestinal cells. To clarify the entire process of the pathobiology of TDH and TRH, including its amyloidogenic/aggregative properties upon heating or in a hydrophobic membranous environment, future studies will be needed. We are grateful to Dr Takashi Fukui (Laboratory of Microbiology and Immunology, Faculty of Pharmacy, Chiba Institute of Science) for participating in valuable discussions. This study was supported in part by grants-in-aid from the Ministry
of Education, Culture, Sports, Science and Technology (MEXT), Japan; Ministry of Health, Labor and Welfare, Japan; Megestrol Acetate The Foundation for Mother and Child Well-being, Osaka, Japan; and Osaka Research Society for Pediatric Infectious Disease, Osaka, Japan. Fig. S1. Each 0.1 mg mL-1 TDH (A), TRH (B), concanavalin A at pH 5.1 (C) and pH 7.4 (D) was incubated for 20 min at the respective temperature. ThT fluorescence was measured according to the procedures described in Materials and methods. Please note: Wiley-Blackwell is not responsible for the content or functionality of any supporting materials supplied by the authors. Any queries (other than missing material) should be directed to the corresponding author for the article.